The past decade has been marked by spectacular advances in the areas of genetic engineering, computer technology and in the implementation of sophisticated instrumentation for the study of biological macromolecules. These advances have made possible the development of new approaches to the study of the structure- function relationships in macromolecular systems and particularily in complex assemblies of biological macromolecules like protein- protein, protein-membrane, and protein-DNA complexes to name only three examples. Central to the development of a rigorous, quantitative description of biological structure and function is a knowledge of the forces and the magnitude of the forces involved in the formation of biological structures as well as the energetics of the molecular interactions associated with biological function. The importance of calorimetry, within this context, is that it is the only technique that allows a direct measurement of the magnitude of the forces and energetics associated with biochemical processes. The Biocalorimetry Center at the Johns Hopkins University, the first of its kind in the country, will have a dual commitment. It will provide a user-oriented facility to aid research scientists in the determination of thermodynamic properties of biological systems using state-of-the-art calorimetric instrumentation (high sensitivity differential scanning calorimetry, isothermal reaction calorimetry and multifrequency calorimetry); and, it will focus in the development of new, supersensitive instruments capable of accurately measuring the energetics of biological processes at the subnanomolar level.